I had wondered that same thing, but didn't bring it up. His developer is nothing like ours so I didn't think of it in this context. So yes, he may have gone down the same path but with a different formula. Very good idea to try a very long development time and see what happens.

PE

Alan Johnson

01-03-2012, 01:54 PM

Mark,
I developed APX100 24min 20C and got good negs in your last posted brew.Maybe a bit overdeveloped.
Gainer found that to get max contrast for a given development time you need 40:1 ascorbate/phenidone ratio.
http://unblinkingeye.com/Articles/Synergism/synergism.html
Xtol has about this ratio.
With no buffer to get pH~8 you have 2.7:0.18 only 15:1.
So you have to develop a lot longer than Xtol to get the contrast.

Michael R 1974

01-03-2012, 03:17 PM

With TMX film my normal XTOL times at 1+3 are over 20 minutes.

albada

01-03-2012, 06:20 PM

Mark,
I developed APX100 24min 20C and got good negs in your last posted brew. (snip) With no buffer to get pH~8 you have 2.7:0.18 only 15:1.
So you have to develop a lot longer than Xtol to get the contrast.

How does the grain look compared to other developers you've used? Hmm, at 100 speed, maybe you'll need a 100x microscope to tell. Also, did the developer turn yellow? And what agitation-method do you use? I agitate for 6 sec, once per minute.

Regarding 15:1: The paradox is that this formula is the nearly the same as PC-Sulfite, except for a different alkali. And PC-Sulfite only needs around 7.5 minutes, operating at the same pH. I've been thinking that dissolved oxygen was destroying ascorbate, but maybe not.

could you find out whether that clip ever turns normal if you dev long enough? (snip) If your test clip turns normal after much longer dev, it would be interesting to see results, especially with regard to grain. On the one side you achieved extra slow development, on the other side you omitted Na2SO3 which acts as a grain solvent.

I'll re-mix and try that, but it looks like Alan beat me to it. :) Anyway, I'll try both normal and continuous agitation.
The possibility of micro-crippling due to poor buffering also occurred to me while driving to work this morning. I got some thin-but-probably-usable negs, and I'll re-examine them for shadow-detail.

TEA has some solvent ability, so 20+ minutes in it might do nice things for the grain. Although at only 5 ml/L, I'm not holding my breath.

For those who want to experiment with this, you can multiply the amount of TEA and AA by the same factor, and the pH will change only slightly. That might be a way to get enough TEA in there to improve buffering and get some solvency-effect. Also, the AA/phenidone ratio will rise by that factor, which will also increase activity somewhat proportionately until levelling off after the ratio goes above 40.

Mark Overton

Alan Johnson

01-03-2012, 06:29 PM

You might keep an eye open for an increase in shadow speed.
Sometimes when a developer takes a long time to reach normal contrast this gives the shadows extra time to develop.Maybe not with sulfite as some of the latent image specks are dissolved, but TEA may do this.

albada

01-04-2012, 03:57 PM

Following Alan's example, I developed the new strip for 20 minutes at 20.5C. The results compared to XTOL:

It seems to me that this developer needs a halide-solvent to improve grain and speed.

Mark Overton

albada

01-05-2012, 12:16 AM

Well, try using Potassium Sulfite.

Regarding solvent-power, how much Potassium Sulfite should I use? The molar-equivalent of Sodium Sulfite?

I ordered some 48% concentrate today, along with Dimezone-S.

Mark Overton

Alan Johnson

01-05-2012, 03:54 AM

It seems to me that this developer needs a halide-solvent to improve grain and speed.

Mark Overton

If you want a glycol only developer with no sulfite,it has been done. But it looks like quite a research project to me.
http://photo.net/minox-camera-forum/00VpUe
That has a lot of phenidone and little ascorbate as it is for microfilm.
1,2-propanediol is propylene glycol.
Notably is appears to use thiocyanate as silver halide solvent.
There are hazards with this but thiocyanate is used in toner.

Photo Engineer

01-05-2012, 11:08 AM

Mark;

Start with the molar equivalent.

PE

Rudeofus

01-05-2012, 02:31 PM

And make sure you properly account for bound water molecules when comparing sodium and potassium sulfite. IIRC both come with varying amounts of water per molar unit, make sure you know which one you have in front of you.

albada

01-10-2012, 09:06 PM

And make sure you properly account for bound water molecules when comparing sodium and potassium sulfite. IIRC both come with varying amounts of water per molar unit, make sure you know which one you have in front of you.

Will do, and thanks for the heads-up.

Another chemistry question: What would be a good acid to mix into TEA to adjust pH and provide decent buffering?

I'm thinking of using only TEA (and no PG) as the carrier for the concentrate, about 22 ml of it per liter of developer. That'll push the pH too high even with the ascorbic acid in it, so another stronger acid is needed to pull it down. I'm hoping that 22 ml of TEA plus an acid to convert some TEA into its conjugate acid (pKa=7.8) will provide sufficient buffering to hold the pH at 8.2 or so. The question is: which acid?

Thanks,

Mark Overton

Rudeofus

01-11-2012, 04:35 AM

Here's a list of acids or acidic substances I have found in b&w developers which I think do not act as development or chelating agent: boric acid, sodium metabisulfite, salicylic acid.
Salicylic acid is soluble in organic solvents so this could be perfect for your recipe. Ryuji uses it in his DS-12 formulation!

Thanks, Mark, for your great efforts! Based on your thread here I have just ordered a bunch of raw chems and will be ready to try out some stuff in the near future. Right now I'm a little bit worried about heating TEA in my flat with two small children around (they have sustained 4 years of E6/C41 so far :P) but I have access to a dark room once a week so we'll see how far I get.

Alan Johnson

01-11-2012, 07:25 AM

Mark,
Xtol contains~0.2g/L dimezone S (phenidone derivative),sulfite @ 85 g/L is a good solvent.
PC-TEA 1:100 contains 0.025g/L phenidone, sulfite @50g/L was not a good solvent in my test at pH ~8:
http://www.apug.org/forums/forum37/31710-pc-tea-sulfite.html
If my result was right, the sovent effect depends on the concentration of phenidone-ascorbate in the working solution as well as the sulfite.
It looks like your concentrate, when decided upon, after dilution will give a phenidone concentration beween the two quoted above.
I hope you get a good solvent effect if a fine grain is the wanted result.

Ryuji

01-11-2012, 02:58 PM

Here's a list of acids or acidic substances I have found in b&w developers which I think do not act as development or chelating agent: boric acid, sodium metabisulfite, salicylic acid.
Salicylic acid is soluble in organic solvents so this could be perfect for your recipe. Ryuji uses it in his DS-12 formulation!

Thanks, Mark, for your great efforts! Based on your thread here I have just ordered a bunch of raw chems and will be ready to try out some stuff in the near future. Right now I'm a little bit worried about heating TEA in my flat with two small children around (they have sustained 4 years of E6/C41 so far :P) but I have access to a dark room once a week so we'll see how far I get.

There are lots of acids that can be used. Malic acid, citric acid, gluconic acid, phosphoric acid, sulfamic acid, sulfuric acid, etc. However, the idea of using triethanolamine as the carrier solvent is probably unwise for practical reasons.

Also, many of the acids above have interaction with iron, potentially useful but potentially harmful. Also, technical grade of those acids may contain a significant amount of iron as impurities. I'd be careful in choosing ingredients.

If anyone wants salicylic acid, I have a LOT of them and don't plan to use much more of them, so I'd be happy to unload some. Email me directly.

Rudeofus

01-11-2012, 03:39 PM

What about EDTA? It's acidic and used in color chems to remove iron introduced by impure Na2SO3.

Ryuji

01-11-2012, 03:41 PM

I've discussed EDTA, NTA and DTPA many times in the past. There are reasons why I don't use them.

Photo Engineer

01-11-2012, 03:41 PM

In B&W developers, the Dequest series of chelating agents are better wrt Iron.

PE

Rudeofus

01-12-2012, 03:02 PM

PE, Mark was looking for acids which don't interfere with the other parts of his developer other than lowering pH. The dequest products you suggested seem to be alkaline to my highly untrained eye. The combination of phosphonates you suggested and one of the acids Ryuji suggested might do the trick, though, lowering the pH and taking care of iron.

Photo Engineer

01-12-2012, 03:40 PM

I have used Dequests that were in the free acid form and had very low pH. I could therefore adjust the pH to any value I wished.

PE

Rudeofus

01-12-2012, 03:57 PM

Are these Dequests substances a normal person outside a lab would have access to? As far as I have understood this, Mark is no chemist, neither am I, and neither one of us has access to "special stuff". I didn't even get (NH4)2 FeIII EDTA here . Marks and my approach to mixing devs seems very different from yours and Ryujis ....